# Fisica

**A 5.0-kg object slides down a surface
inclined at an angle of 30o from the horizontal. Friction may be neglected. The total
distance moved by the object along the plane is 10 meters. The work done on the
object by the normal force exerted on the object by the surface is most nearly **

·0 kJ

**An object moves halfway around a circle
of radius ***R***. An inward radial force of magnitude ***F ***is
The work done on the object by the radial force being exerted on it is **

·zero

**A person exerts a constant force of 45 N
directed at angle ****
****100 N to pull it from one end of a room
to another, a distance of 4.0 m. Given that the vertical component of the force
is 12 N, calculate the work done by the person on the crate.
**

·1.7 x 10^2 J

**A donkey is attached by a rope to a
wooden cart. The rope makes an angle of 23o to the horizontal. The tension in the
rope is 210 N. If the cart is pulled horizontally along the ground with a
constant speed of 6.0 km/h, calculate how much work the donkey does on the cart
in 35 minutes. **

·680 kJ

**A variable force is represented on an ***F***-versus-***x ***graph.
Which of the following is the work done by this force?
**

·the area bounded by the curve and the *x *axis

**An object on which a variable force is
exerted travels a distance of 20 m in a straight line in the same direction as
the force. The graph shows the force exerted on the object as a function of the
position. What was the total work done by this force on the object during the
full 20-m trip?
**

·60 J

**A block is pushed on a horizontal surface
by force, ****. The surface exerts a force of friction ****on the block. If the block undergoes a
displacement ***d ***at constant velocity, the net work done
on the block **

·is zero.

**A 6.0-kg block slides from rest at
position ***A ***down a frictionless incline to position ***B***.
the block at ***B ***is **

·4.4 m/s

**A skier of mass 50 kg is moving at speed
10 m/s at point P1 down a ski slope with negligible friction. What is the
skier’s kinetic energy when she is at point P2, 20 m below P1? **

·12300 J

**A mass ***m ***=
2.5 kg is sliding along a frictionless table with initial speed ***v ***as
shown in the figure. It strikes an uncoiled spring of force constant ***k ***=
500 N/m and compresses a distance of 5.0 cm. The initial speed ***v ***of
the block was **

·0.71 m/s

**A mass on a frictionless surface is
attached to a horizontal spring of spring constant ***k ***and
set into motion by being displaced from its equilibrium position ***xi ***a
distance ***A ***and released. Which of the following
graphs best represents the kinetic energy as a function of displacement when
the mass moves on its own from position ***xi ***to
position ***A***? **( d ) iII

**A ball of mass ***m ***is
dropped from an initial position at height ***h***1
above a reference point. The ball is observed in three positions A, B and C, as
indicated in the figure. Which of the graphs shown best represents graphs of
the kinetic energy ***K***, gravitational potential energy ***U***,
and total mechanical energy ***E ***of the ball-Earth system at positions A,
B and C? **

·A →Graph (F), B →Graph (E), C →Graph (A)

**An object falls through the atmosphere
gaining 20 J of kinetic energy. If air resistance is not negligible, how much
gravitational potential energy is transferred out of the object-Earth system? **

·more than 20 J

**A woman on a bicycle traveling at 10 m/s
on a horizontal road stops pedaling as she starts up a hill inclined at 3.0o to the
horizontal. If friction forces are ignored, how far up the hill does she
travel before stopping?
**

·97m

**A simple pendulum has a bob of mass ***m***.
fixed
at I. At position ***A***, the string is horizontal and the bob is
at rest. The bob is released from I and swings to ***B***,
where the string is vertical. The tension in the string when the bob first
reaches I is **

·3*Mg *

**A roller coaster starts from rest at
point A. If you ignore friction and take the zero of potential energy to be at
C, **

·the kinetic energy of the coaster at C will be equal to its potential energy at A

**A force of 6.00 N directed at the angle
of 40.0o relative
to the ground moves a 1.00 kg block a distance of 0.250 m in 2.00 s. What is
the power delivered to the block by the force? **

·0.574 W

**A uniform 12-inch ruler has a 5-g mass at
the “1-inch” mark, and a 10-g mass at the “7-inch” mark. Where is the system’s
center of mass? **

·Between the “1-inch” mark and the “6-inch” mark

**A wheel is rotating at 30 rev/min. The
angular velocity of the wheel is **

·i rad/s

**A wheel on a car is rolling without
slipping along level ground. The speed of the car is 36 m/s. The wheel has an
outer diameter of 50 cm. The speed of the top of the wheel is **

·72 m/s

**A wheel rotates with a constant nonzero
angular acceleration. remains constant in magnitude? **

·tangential acceleration

**A perfectly spherical orbiting
communications satellite is in a circular orbit about Earth. The torque exerted
on the satellite by the gravitational pull of Earth is**

·zero.

**An object that moves with a constant
speed in a circle **

·has no work done on it

**A cylinder (***I***cylinder
= cylinder is _____. ***MR***2****) rolls along a level floor with a speed **

·¾ mv^2

**If mechanical work is done on an object,
the object must **

·accelerate

**If the momentum of an object of mass ***M ***is
doubled, its kinetic energy will be multiplied by a factor of**

·4

**In a center-of-mass reference frame for a
system with no external forces applied to it **

·the total momentum is zero

**Negative work means
**

·the angle between the displacement vector and force vector is larger than 90º

**The
SI unit of energy can be expressed as **

·kgm2s2

**Two skiers start at the same place and
finish at the same place.
poles during the trip. They both just slide along
their chosen path. Skier A takes a straight, smooth route to the finish whereas
Skier B takes a curvy, bumpy route to the finish. If you assume that friction
is negligible, which of the following statements is true? **

·Skier A has the same speed as skier B at the finish.

**The graph represents the force ***F ***exerted
on a object plotted versus the displacement ***x ***of
the body in The total work done by the force from ***x ***=
0 to ***x ***= ***x ***is
**

·1/2 *mx*2 +*bx *

**The block shown is released from rest on
a frictionless ramp. Its speed when it reaches the level portion of the surface
on which it is sliding will be **

·7.67 m/s

**The block shown is released from rest on
a frictionless ramp. It slides 9.0 m on the rough, level surface before
stopping. What is the coefficient of kinetic friction between the block and the
level surface? **

·0.33 m/s

**The surface shown in the figure is
frictionless. The block is released from rest. What will be the maximum
compression of the spring? (Provide three significant digits in the final
answer.) **

·0.989 m

**Two identical air-hockey pucks are moving
on an air-hockey table with an ***x***–***y ***axis
drawn upon it. Puck ***A ***has a velocity of 5 m/s at an angle of 35
degrees above the ***x***-axis. Puck ***B ***has
a velocity of 6 m/s at an angle of 70 degrees above the ***x***-axis.
Which puck has a larger momentum in the ***x***-direction?
**

·Puck *A *

**Two objects, one of mass ***M, ***and
the other of 5***M ***rest on a horizontal frictionless table
with a compressed spring of negligible mass between them. The spring is
released and each object gains kinetic energy. The object of mass ***M ***gains
**

·5/6 of the energy

**Two students, initially at rest, sit on
carts with frictionless wheels. The mass of student 1 and her cart is ****M****, and the mass of student 2 and her cart
is 1.5****M****. The students push against each other
and roll in opposite directions. If student 2 moves with velocity ****, what is the velocity of student 2? **

·+ 2/3 – v

**The condition necessary for the
conservation of linear momentum in a system is that **

·the net external force on the system is zero.

**Two objects of equal mass travel in
opposite directions with equal speeds. If they collide in a perfectly elastic
collision, then, just after the collision, their velocities will be **

·equal in magnitude but opposite in direction to their original velocities

**The center of mass of a system of
particles is so defined that **

·its location depends only on the masses of the particles and their locations.

**Two identical objects, ***A ***and
***B***, are placed on a horizontal platform
that is rotating about an axis through its center at a constant angular
velocity. ***A ***is located at a distance ***R ***from
the axis of rotation, and ***B ***is located at a distance 2***R***.
The angular velocity of ***A ***to the angular velocity of ***B***. **

·is equal to

**The London Eye, a giant Ferris wheel, has
a diameter of 135 m. It revolves at a constant rate and takes 30 minutes to
complete one revolution. What is the linear velocity of a rider in a capsule
that is located at the perimeter of the wheel? **

·0.24 m/s

**The rotational inertia of an object about
an axis depends on the **

·mass distribution about the axis.

**The diagrams show the application of a
force to a level arm. Which diagram has the largest (magnitude) torque about
the hinge?
**

·They are the same

**Which of the following statements about
energy is true: **

·An object’s or system’s energy is related to its ability to do work.

**What is the net work done on a 1500-kg
car when it slows from an initial speed of 96 km/h down to 56 km/h in a
distance of 55 m? **

·–3.5105J

**Which of the following statements is NOT
correct?
**

·The force of friction is a conservative force.

**What is the escape speed from the Sun,
beginning (from rest relative to the Sun) at the orbit of Earth, ***R ***=
1.50 **** ****108 km? (Given: ***G ***=
6.67 **** ****10–11 N **** ****m2/kg2; mass of the Sun = 2.0 **** ****1030 kg.) **

·4.2 x 10^4 m/s

**What physical quantity is represented by
the slope of the curve shown on the graph? **

·angular acceleration

**You are pedaling a bicycle at 9.8 m/s.
The radius of the wheels of the bicycle is 51.9 cm. The angular velocity of
rotation of the wheels is most nearly **